Thermal electrical protector.



U. A. ROLPB.

THERMAL ELEGTRIOAL PROTECTOR.

APPLICATION FILED APR. 21, 1902.

1,005,475. Patented Oct. 10, 1911.

UNITED sTA Es PATENT OFFICE OHARLES A. ROLFE, OF ADRIAN, MICHIGAN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO BOLFE ELEGTRIC 00., OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Oct. 10, 19.1 1

Application filed April 21, 1802. Serial No. 104,022.

To all whom it may concern:

Be it known that I, CHARLES A. HOME, a citizen of the United States, residin at Adrian in the county of Lenawee and tate of Michigan, have invented a certain new and useful Improvement in Thermal Electrical Protectors, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying 1dirawings, forming a part of this specifica- My invention relates to thermal protective devices for protecting low tension circuits such as telephone, fire alarm and the like, from the injurious effects of unduly strong currents such as emanate from electric light and power circuits.

Prominent objects of my present invention are to provide a sim le, practical and inexpensive device of this ind, and to allow 7 the delay incident to repairing the device after it has operated, to be avoided.

The device which I have herein shown for carrying out my invention, involves a spring,

a swinging abutmentadapted to detachably engage the spring and hold the same normally under restraint, a small qgantity of heat susceptible material holding the abutment in position to hold the spring normally under restraint, and a heat concentrating device associated with the small quantity of heat susceptible material and adapted upon the passage of an unduly strong current in the protector, to soften such material and thereby permit the spring to shift the abutment sufliciently to permit its release and the opening of the circuit. In one form of such device herein shown, a plurality of movable abutments are provided and the-spring is arranged for shifting movement so that it can engage any one of such abutments, and the abutments are included in a common circuit. By such arra ment, after one. of the abutments has been shifted by the spring upon the softening of the heat susceptible material associated with such abutment, the spring can the spring under restraint.

is a erspective view of a thermal protectlve evice embodying a portion of my present invention; Fig. 2 is a plan view of a thermal protective device embodying a plurality of abutments; Fig. 3 is a vertical section of the same taken on line 33 in Fig.

- shown an insulating base 1 provided at one end with a spring 2 having a free end 3" which tends to rise or swing upwardly. At the other end of the insulatin support 4 supporting and holding a metal rod 5. At the end of this metal rod 5 is a metallic clip 6 having an aperture through which the rod 5 extends, and having its lower surface made slightly concave, as shown in Fig. 6. The clip 6 is soldered to the metal rod 5 by a layer of solder 7 (Fig. 6). The free end of the spring 2 is provided with a gra hite stick or rod 8 which extends under t e clip 6 and rests in theconcave lower surface thereof, whereby the clip 6 forms an abutment for holding The graphite stick 8 has such internal resistance and the solder 7 is capable of melting at such a comparatively low temperature, that an unduly strong current passing through the devicewill cause the stick 8 to generate sufiicient heat to melt the layer of solder 7 The operation of the device therefore is as follows: During normal conditions, the spring 2 is held in restraint by the cli 6 at the end of the metal rod 5, so that t e circuit is conbasel is a.

tinuous from the spring 2 to the support 4 with whose bases the line is connected. When an unduly strong current traverses the circuit, the graphite stick 8 becomes sufficiently heatedto melt the layer of solder 7 at the end of the rod 5, thereby. loosening the spring and permitting it to swing the clip 6 upwardly and backwardly, in do ing which it frees itself from the clip 6 and breaks the circuit.

The device shown in Figs. 2, 3, 4. and 5 comprises an insulating base 9 made 111 cucular form as shown in Fig. 2. The base9 is provided with a centrally located post 10 whose lower end is threaded and provided with nuts 11, 11, for connection with one of the line wires. Above the base 9 the post 10 is enlarged at 12 and is provided at its upper end with an adjusting screw 13. Be-

' of the enlarged portion 12 of the post are located a spring 14:, and a washer15. A spring 16 is earned by the post 12, the spring having a flat portion 17 arranged between the washer 15 and the top of the enlarged portion 12 of the post, and the remainlng ortion of the spring being arranged in 00 form so as to extend first upwardly an then downwardly. The lower end of the spring is provided with a piece of hi h reslstance graphite 16". The spring as a tendency to move its free end outwardly, shown in Fig. 4. The base 9 is rovlded with a circular metal plate 18, an around the outer edge of this plate are arranged a series of swinging lugs 19, 19, pivotally connected at their lower ends with the plate, as by means of a wire 20 extended around the eriphery of the plate and inclosed in a holow portion 21 formed thereon. These swingin lugs 19, 19, are each provided with a globu e or small quantity 22 of solder capable of melting or softening at a comaratively low temperature, by which the lhg 19 is soldered to the plate 18. As a preferred arrangement I each swingihg In 19 a sma 1 spring 23 tending to swing an hold the upper end of the block in an inward position. These springs 23, 23, are properly secured to the insula; ing base 9. The plate 18 is to be connec to the other side of the circuit as by ,a screw 24. The operation of this device is as follows: The sprin 16 is rimarily arranged so that its grap ite stic or point 16" is inside of the upper end of one of the swinging lugs 19, as shown in Fig. 3, whereby such lug forms an abutment for the graphite point or stick and holds the spring in restraint. So long as the conditions on the line are normal, the device remains in this condition, the circuit being properly closed between the lower-end of the post 10 V and the plate 18 by means of the spring 16,

graphite point 16 and swinging lug 19. When an unduly strong current traverses the line, however, the high resistance graphite 16 is heated to such an extent as to melt or soften the readily fusible solder 22, whereupon the lug 19 is released by such solder and the spring 16 swings outwardly as shown in Fig. 4, thereby reaking the circuit between itself and the end of the plug. As soon as the spring 16 is freed from'the lug 19 with which it was in engagement, the

spring 23 applied to said aplug automatically restores it to its vertic or normal positicn, this being done while the solder is still melted, by reason of the'immediate action of the spring 23, 'A' few minutes are required, however, for the solder to harden to enable the lug 19 to again withst lace outside of strain of the spring 16. If it is desired to use the circuit immediately, the spring 16 is swung about its pivotal connection with the post 10 to one side or the other, and its graphite encil 16 placed in engagement inside of t e upper end of another lug 19,

The device remains in this condition until another unduly stron current traverses the, line, when this secon lug is released, there. by allowing the spring 16 to operate and 0 en the circuit. After thishasoccurred, t e spring 23 for such lug automatically restores it to its normal condition, but to secure continuity of the circuit immediately,

the sprin 16 can be swung so as to make contact with another lug 19, whereu on conditions remain as before until the device is separated by another unduly strong current. In this way the spring 16 can be caused to make connection successively with the various lugs or abutmen'ts 19, 19, of the device so as to allow immediate restoration of the circuit to its normal closed condition and at the same time after each release 0 the spring 16, the abutment hol it is automatically restored to normal con ition; thus the device can be used indefinitely in this way, without requiring any repair or re lacement of parts.

11 an a plication of mine filed [of even date herewith Serial No. 104,021, I have'set forth a somewhat different embodiment of the self-restorin spri 23, 23, and have claimed such sel restor1ng and self-soldering feature broadly. In the present application I shall simply claim its specific application to the present protector. In this application however, I shall claim broadly oer-- tain eatures of construction involved in common in the device of this application, and of my said other application.

With reference to the two devices herein set forth, it will be noted that they have swingin abutment, which is in turn held in position by a small quantity of heat sus- .ceptible material associated with a heat concentrating device by which such material is softened or melted upon the passage of an unduly strong current. The two forms of device also have other features in common which will be noted in the claims.

It will be understood that I consider my present invention capable of much variation and modification and hence do not desire to be limited to the specific structure herein shown and described.

What I claim as my invention is 1. in a thermal protective device, the combmation with a circuit controlling device, of v a plurality of devices coiiperating therewith, means connecting any one of the same in circa: j: and means for restoring each of said devices to operative condition.

' ling-mechanism,

ranged tohold said abutments normally' 11 met movement, a circuit controlling device adapted to be placed in 0 erative relationship with any one of sai abutments and to be restrained thereby, means for affecting the heat susceptible material associated with-the abutment cooperating with said circuit COIltI'OlllIlg device, and means for restoring each abutment to normal position, substantially as described.

3. The combination with a'plurality of abutments, of bodies or masses of heat susceptible material, one for each abutment, arranged to hold said abutments normally against movement, a circuit controlling device adapted to be placed in operative relationship with any one of said abutments and to be restrained'thereby,means for affooting the heat susceptible material associated with the abutment cooperating with said circuit controlling device, and means each abutment to normal posie same has been actuated so as to be swung and while said material is still affected, substantially as described;

4. The combination with circuit controlof a plurality of devices operable by an excess of current, each of said devices being adapted to cooperate wigh the circuit controlling mechanism and bein adapted to be operated b the operation 0 the circuit controlling mec 'anism, and means for automatically restoring each of said excess operated devices.

5. The combination of'a centrally mount- Zed pivotally connected spring, a plurality of, 7

Y swinging abutments arranged 1n annular ot'all connected with sai series, each of which is adapted to engage and restrain the free end of said spring,

heat susceptible material holding said abutments in position to restrain the sprin springs for restoring said abutments to sue position and means whereby the heat susceptible material for any abutment can be melted or restrained by such abutment.

6. The combination of a base provided with a centrally located 0st, a spring pivost so as to permit it to swing readily and having its free end provided with a graphite stick, a metal plate on the base provided with a plurality of pivotally supported abutments arra ed in annular series, and small quantities of readily softenable solder for holding said abutments in normal position, substantially as described.

7. The combination of abase provided mit operationof said spring, means for automatically returnin softened upon the passageof an unduly strong current when the spring iswith a centrally located otall connected with sai 0st so as to rmit it to swing readily and having its ree end provided with a graphite stick,.a metal plate on the -baseprovided with a plurality of pivotally supported abutments arranged in annular series, small quantities of res. ily softenable solder for holding said abutments in normal position, and springs for automatically restoring the abutments to normal position, substantially as descri 8. An electrical circuit protector comprispost, a spring piv-- ing a plurality of devices m contro the circuit, adapted and arranged. for use at different times, and having 1provisions whereb said devices :automatica y restore themse ves to operative condition.

9. An electrical circuit protector, com rising a plurality of devices for vcontro ing the circuit, adapted and arranged for use one after another, and having provisions where' by said devices are automatically resoldered in operative condition.

10. An .electrical circuit protector comprising a plurality of'solder-joint devices for opening t e circuit, said devices being arranged for use at different times, and having provisions whereby said devices automatically resolder themselves, after operation.

An electrical cirfuith retepto r, cog: prising a spring, a are t o mova solder-secured devices for holding saidspring in restraint, said devices'being comstructed to automatically resolderthemselves in operative condition, and means-tor softens ing the solder of said devices to release'them and permit operation ofthe spring.

12. An electrical cireuitfprotector comprising a spring, a plurality of solder-secured devices each adapted to. hold said spring in restraint,means whereby the solder joints of said devices can be softened to perand spring said devices to their ori al 'tions a er. operation, whereby suc devices are automatically reset and resoldered after operation.

13. A spring-actuated electrical circuit protector normally held in restraint by a device constructed to restore itself automaticallyafter operation to condition. to hold the protector again in restraint, and having a plurality of such devices adapted and arranged for use one after'another.

In witness whereof, I hereunto subscribe my name this 7th day of April A. D., 1902.

CHARLES A. ROLFE.

Witnesses;

-' MnmBnnrmm,

I Clam. 

